Bacterial community structure and metabolic profiles in a forest soil exhibiting spatially variable net nitrate production

High spatial heterogeneity in nitrification potentials has been observed in the top soils of a pine forest. In the present study the bacterial community structure, function and activity was determined in an acid forest soil and their relationships to spatial variation in net NO3−‐N production were analysed. The bacterial richness, determined by 16S rDNA DGGE fingerprinting showed more variation between samples from the same soil than the substrate utilisation patterns. Differences in microbial transformations such as NH4+‐N or NO3−‐N production were not correlated to bacterial diversity and community structure. Nonetheless, there was a positive significant correlation between N-mineralisation and nitrification, indicating that ammonium production is an important regulator of nitrification in this soil. The combined results showed that this forest soil contains a highly diverse bacterial community with a limited number of strongly dominant species, variable in space and a limited number of nitrifiers.